Exemplary embodiments of the present invention relate to a device for regulating the pressure and/or mass flow of a gaseous or liquid fluid, which can be conveyed through a line, in particular for a space propulsion system.
Mechanical pressure regulators are typically used for regulating the pressure and/or mass flow of gases or liquid mediums in a space propulsion system. An operating point, such as a control pressure, is set during manufacture of the mechanical pressure regulator. When such a pressure regulator is used in space applications, the components are often manufactured months or even years before the component is used in space. Subsequent changes in the operating point, in particular when the space component is already in orbit, are no longer possible or are possible only with considerable effort.
Exemplary embodiments of the present invention are directed to a device for regulating the pressure and/or mass flow in such a way that the device is improved in terms of design and function. Exemplary embodiments of the present invention provide a device for regulating the pressure and/or mass flow of a gaseous or liquid fluid that can be conveyed through a line. Such a device may be used, for example, in space propulsion systems of any kind in order to implement the supply of pressure to the mediums to be conveyed or for regulating the mass flow rates of mediums.
A combination of a first, piezoelectrically actuatable regulating valve and at least two second, magnetically actuatable regulating valves is provided for regulating the pressure and/or mass flow of the fluid. The regulating valves are connected to each other and to a line input in such a way that in a nominal mode the pressure and the mass flow of the fluid in the line can be set by means of the at least one first regulating valve, and a connection or isolation of the first regulating valve with or from the line input can be produced by means of the second regulating valves. In an emergency mode the pressure and the mass flow of the fluid in the line can be set by means of the second regulating valves.
The device can be used, in general, in all such areas, in which high pressure levels at the line input are to be reduced to low pressure levels at a line output by means of the device.
In contrast to conventional mechanical pressure regulators, the device of the present invention is based on an electric control of a plurality of valves. The regulating of the pressure and/or mass flow of the fluid to be conveyed is achieved by a combination of solenoid valves and piezo valves. Exemplary embodiments of the present invention employ the solenoid valves for both regulating and shutting off.
One advantage of the device is the fact that the operating point, for example a control pressure, can be set by means of software at a later point in time. In the extreme case the setting of the operating point can take place when the device is used in a space propulsion system, even in orbit. The ability to change the operating point allows for realization of various applications. For example, the device can be used in supplying pressure to electric, chemical or cold gas propulsion systems or for regulating the mass flow rate in electric drive systems.
An additional advantage of the device is that due to the high degree of tightness, which is achieved by means of the solenoid valves, it is possible to significantly extend the operating time in orbit, possibly even until the end of a mission. In contrast to conventional devices, the proposed device exhibits a longer and more efficient operation, a feature that is an economic factor for an operator of a space device. This more efficient operation is due to the fact that in a conventional device the mechanical regulators are permanently isolated once a space component has been positioned, and a remaining propellant is pumped out with the residual pressure in the tank. As a result, the space propulsion system is not operated at the optimal operating points and consequently exhibits lower efficiency.
In addition to the above described advantage, it is possible to take any necessary corrective action in the event of anomalies in the space propulsion system.
In particular, it is possible to switch the device over into an emergency mode, in order to ensure the regulating process by means of the solenoid valves, even if the piezoelectric regulating valve that is used for regulating the pressure and/or mass flow has failed. In the normal mode the device can be precisely reset by means of the piezoelectric regulating valve, because this regulating valve exhibits a proportional opening characteristic. Of course, such a precise regulating process is not possible with the use of the solenoid valves in the emergency mode because these solenoid valves do not exhibit a proportional opening characteristic. Instead, these solenoid valves can only be opened or closed. Nevertheless, an emergency mode can be maintained in the event of a malfunction.
In a first variant, one of the second regulating valves is connected in series with the first regulating valve between the line input and the regulating valve. Another one of the second regulating valves is connected in parallel to the first regulating valve. This design variant enables a “bypass” of the first regulating valve, if, for example, this first regulating valve can no longer be opened.
On the other hand, when the device is isolated, according to the specifications, from the line input (i.e. no fluid is conveyed to a consuming component), the tightness of the device can be enhanced in a targeted way by connecting in series a second regulating valve with the first regulating valve.
In an additional variant, one of the second regulating valves is connected in series with the first regulating valve between the line input and the regulating valve. Another one of the second regulating valves is connected in parallel to the series connection consisting of the first regulating valve and the one of the second regulating valves. This variant makes it possible to separate a first regulating valve, which can no longer be closed, from the line input by means of the series connected second regulating valve and to make a connection between the line input and a line output by means of the parallel connected second regulating valve.
According to a second design variant, the first and the at least two second regulating valves are assigned to a regulating unit. The regulating unit is connected to the line input by way of a supply unit. The supply unit has at least one third, magnetically actuatable regulating valve for connecting or separating the regulating unit to or from the line input. By providing the supply unit between the line input and the regulating unit, which can be configured according to the above described design variants, it is possible to improve the tightness of the device in the event that it is necessary to separate the regulating unit from the line input.
In order to be able to generate a high degree of tightness of the device, even in the case of a defect of a third regulating valve of the supply unit the supply unit can comprise at least two third regulating valves that are connected in series to each other.
In an additional embodiment the regulating unit comprises a first valve train and, connected in parallel thereto, at least one second valve train with the first and second regulating valves respectively. The first valve train constitutes a primary branch, and the at least one second valve train, which is connected in parallel to the first valve train, constitutes a redundant branch. As a result, the reliability of the device is guaranteed even if the complete valve train malfunctions.
Corresponding hereto, the supply unit can comprise a third valve train and, connected in parallel thereto, at least one fourth valve train with the third regulating valve or third regulating valves respectively. In this case the third valve train constitutes a primary branch, and the at least one fourth valve train, which is connected in parallel to the third valve train, constitutes a redundant branch.
The number of redundant branches in the regulating unit and/or the supply unit can be selected as a function of the desired fail safety of the device.
Similarly it is possible, according to one embodiment, to form the first and the second valve train of the regulating unit in an identical way or in a different interconnection of the first and second regulating valves. For this purpose, in particular, the two design variants described above may be considered.
Furthermore, the first and the at least two second regulating valves can be actuated by a control unit. The control unit comprises driver electronics, which sets off the target and actual values of the pressure in the line and then from the results computes and executes the actuation of the various regulating valves. In particular, in this case the control unit for controlling the regulating valves of the device can be fed the target values and the measurement values of the pressure and/or the mass flow of the fluid.